Chargers-49ers, 5 things to watch

Indianapolis Colts inside linebacker Kavell Conner (53) after a tackle on Kansas City Chiefs running back Knile Davis (34) during the first half of an NFL wild-card playoff football game Saturday, Jan. 4, 2014, in Indianapolis. (AP Photo/Michael Conroy)
The Associated Press

Indianapolis Colts inside linebacker Kavell Conner (53) after a tackle on Kansas City Chiefs running back Knile Davis (34) during the first half of an NFL wild-card playoff football game Saturday, Jan. 4, 2014, in Indianapolis. (AP Photo/Michael Conroy)

The Chargers and 49ers will meet Sunday in each team's most significant tune-up of the four preseason exhibitions. Here are five developments to watch:

• Shuffling at inside linebacker -- With Manti Te'o (foot) out after starting both exhibitions, it's expected that Kavell Conner will work next to Donald Butler in the base defense. Speedy Andrew Gachkar and Reggie Walker will play as well. The Butler-Conner pairing is one to watch because Conner's presence could put Butler into more of a playmaking role, similar to when run-stuffer Takeo Spikes was next to him. Butler did some of his best work next to Spikes. Conner may be less stout than Spikes was in his first season with San Diego. But he was a 36-game starter with the Colts. Does he know the system well enough to take on some of Butler's playcalling? Also, Conner is a few pounds heavier than Te'o.

• Run defense? -- The Chargers have missed too many tackles this preseason. Injuries weakened the line and its depth. Blockers knocked around healthy end Kendall Reyes on a few plays. The run D has been ugly at times, even worrisome. Ominous? Not necessarily. Consider that 1) the Chargers did NOT game-plan for Seattle's offense. The Chargers' pocket-based offense is much different from Seattle's design -- which makes heavy use of bootlegs -- and that's the only offense the Chargers' D prepared against leading up to the game. 2) the Chargers are flip-flopping ends Reyes and Corey Liuget. Being less predictable with Liuget, the front's best player, paid off in the playoff win at Cincinnati. But it's an adjustment for Reyes too. 3) The inside linebackers have been in read-and-react mode, which makes it easier for blockers to double-team Chargers linemen. Nevertheless, the inside linebackers have not been firing off and finishing as one would like. Te'o, in particular, looked tentative at Seattle, though John Pagano praised his work versus Dallas and in practices.

• Protect Philip Rivers -- The 49ers, like the Seahawks, have a great pass rush. In Seattle, the Chargers responded by protecting No. 17. It was a credit to Rivers, Frank Reich and blockers. Expect Rivers' snap total rise Sunday. The Chargers would like his hit total to remain at zero.

• Good traction? -- Poor field conditions at the 49ers' new stadium led Jim Harbaugh to cut short Wednesday's practice. Thursday, the 49ers began installing a new field. Mike McCoy said the 49ers assured him conditions will be fine by Sunday. The $1.3 billion stadium, built with taxpayer assistance, opened just this month. Hazardous field conditions are the last thing the NFL would want.

• Fundamentals and flow -- This is a repeat category. Truth be told, the Chargers are probably more interested in nailing the fundamentals -- which improve the chances of staying healthy -- than winning the game. As always, McCoy will demand crisp, efficient communication that gives Rivers and defensive leaders time to make calls and adjustments.